Never had a ray refuse worms… they are also extremely hard to get off worms. U have to chop up worms and soak them in other foods like shrimp and pellets to get them on other foods. U need to offer this mix 2-3 times a day every day when there small. It can take several months of doing this to convert them onto other foods. Some switch over easily others do not. IME, rays get locked onto one type of food and become very picky. Even being a pup ur ray should be eating a half a dozen worms every day. Offer 1-2 crawlers per feeding multiple times a day to fatten it up. All sellers purge their rays before shipping so they come in under weight. If its on worms only, might want to look into European crawlers. U can keep them at room temp in a bucket with news paper opposed to in the fridge. There a bit smaller but last much much longer than canadian crawlers in the fridge. Check out “uncle jims worm farm”… he has the canadians. I used to buy them by the thousand. U might have a long road of working with ur pup to get it onto shrimp/cut fish and then onto pellets. Might get lucky tho also. U really have to be persistent offering things multiple times a day and removing the uneaten food. Ull prob break before they do lol… just how it goes.